Rats and non-human primates will be exposed to oxidant air pollutants of a photochemical type, primarily ozone and nitrogen dioxide, at concentrations approximating high ambient levels. Structural-functional correlates of the effects will be assessed by integrated physiologic, morphometric and biochemical studies. Specific pathogenetic relationships to be sought, by determination of appropriate parameters, are: 1) Between changes in pulmonary function and morphometry of airways, alveoli and the blood-air barrier. 2) Between decreased resistance to infection and enzymatic defects and lipid peroxidation in pulmonary alveolar macrophages. 3) Between morphometry of the blood-air pathway and lipid peroxidation. Other hypotheses to be tested concern the concept of oxidant lung damage as an acceleration of lipid peroxidation-molecular damage and the possible prophylactic effect of diets with increased content of vitamin E and other antioxidants.